Method of joining wire or rods of compound material with aluminum core and copper casing

ABSTRACT

For joining wire of compound material having a core of aluminum and a casing of copper, the ends to be joined are shaped to form male and female parts, the male part is inserted in the female part, and a sleeve of explosive is applied around the joint and detonated so that the core and casing are joined in one operation by explosion welding.

United States Patent 1 1' 3,868,762

Nilsson Mar. 4, 1975 METHOD OF JOINING WIRE 0R RODS 0F 3,263,323 8/1966Maher et a1. 29/421 x COMPOUND MATERIAL WITH ALUMINUM 3,223,831; 3/1323fiordokg ..l 537238.; 52

, yser 0 et a O AND COPPER CASING 3,535,767 lO/l970 Doherty, Jr. et al29/4975 X [75] Inventor: Jan Nilsson, Robertsfors, Sweden 3,563,7132/1971 Rudd 29/4701 UX 3.612.748 5/1971 James 102/28 X [73] Asslgneefsvenska Elektl'lska 3,684,820 8/1972 Johnsen 29/628 x Aktrebolaget,Vasteras, Sweden [22] Filed: Jan. 13, 1972 0 Primary E.t'aminerJ.Spencer verholser [21] Appl 217512 Asxislan! l;'.\'aminer-Ronald J.Shore [30] Foreign Application Priority Data Jan. 29, 1971 Sweden1073/71 [57] ABSTRACT Mar. 11, 1971 Sweden 3106/71 For joining wire ofcompound material having a core [52] US. Cl. 29/470.1, 29/628 ofaluminum and a casing f copper, the ends to be [51] Int. Cl 823k 21/00joined are shaped to rm mal and ale parts, th [58] Field of Search29/421 E, 4701, 486, 4975, male part is inserted in the female part. anda sleeve of 29/623 explosive is applied around the joint and detonatedso that the core and easing are joined in one operation by [56]References Cited explosion Welding 1 UNITED STATES PATENTS I I 2,367,206I l/l945 Davis 29/421 9 Claims, 7 Drawing Figures 70 26 7b 20 lo [Ill/l////l/Il/l/I/' III/I/U I/ PATENTED 41975 3,868,762

sum 1 mi 3 I I I I/I/ Fig.3

WWW/W777? METHOD OF JOINING WIRE OR RODS OF COMPOUND MATERIAL WITHALUMINUM CORE AND COPPER CASING BACKGROUND OF THE INVENTION 1. Field ofthe Invention The invention relates to the joining of wire or rods ofcompound material with an aluminium core and a copper casing.

2. The Prior Art Hydrostatic extrusion straight down to the desiredfinal dimensions is uneconomical with very thin wire since thepermissible cylinder pressure limits the extrusion ratio. The upperlimit when extruding compound wire having an aluminium core and coppercasing is less than 2,000, usually less than 1,000. The extrusion ratiopossible decreases with increasing copper content. Thus, the extrusionratio which can be achieved limits the weight of the billet. For highproduction and good economy in a press for hydrostatic extrusion theextruded wire must have a diameter of at least mm. A diameter of 6 10 mmhas been found to be extremely suitable for copper-aluminium wire.Lengths of l,000 m and more can be obtained from one billet. The wireobtained can be machined by drawing to the desired dimension. When theextruded wire is drawn to a diameter of 0.4 mm, about 250,000 metres ofwire are obtained from a single billet, which is more than enough formost purposes. However, lengths of 1,000 m are unsatisfactory asstarting lengths for drawing in a drawing machine, since in principledrawing is a continuous method which requires enormous starting lengthsif the production costs are to be kept low. A number of extruded lengthsof wire must therefore be joined together in order to acquire lengthswhich can be economically drawn. It has been found extremely difficultto join compound wire having an aluminium core and copper casing,however, in such a way that it can be drawn. Most welding methodsinvolve such alterations in the material at and around the joint thatthe wire breaks during the drawing process. One of the main reasons forthis is that hard and brittle alloys are formed in the boundary layerbetween the casing and the core when the wire is heated. Thisalteration, which also causes hardness and greater brittleness at thejoint, causes complications when drawing the wire to smaller dimensions.The drawing resistance alters when the joint passes a drawing plate andthis may give rise to jerks so that the wire breaks. The brittleboundary layer may also be broken during the drawing so that the coppercasing separates from the aluminium core and flakes off during thedrawing process.

By joining the wire by means of pressure welding and removing the bulgethe problem of hard compounds has been solved, but unfortunately a jointis obtained which has no casing. This type ofjoint also causes problemsduring drawing. Furthermore, the wire at the joint has other propertiesand a different appearance from the rest of the wire. In order to obtaina compound wire with uniform properties the joint has been provided witha new casing by joining a sleeve with the core and with the casings oneither side of the joint by means of blast welding.

Compound wire having a core of aluminium and a casing of copper has alsobe joined by exposing the core at the joint and welding together thecores of the two wires, for example by means of electron-beam 2 welding,and then applying a casing over the joint by means of blast welding asleeve or parts of the casing which was removed from the core and bentback so that the cores were accessible for welding.

By explosion welding is meant a welding method in which a material isinfluenced by a pressure wave and thus pressed against another materialwith such force that the two materials become metallically bonded.

SUMMARY OF THE INVENTION The present invention relates to a methodofjoining wire of compound material having a core of aluminium and acasing of copper. According to the invention, the wire ends to be joinedare shaped to form male and female parts, the male part is inserted inthe female part, and a sleeve of explosive is applied around the jointand detonated so that the core and casing are joined in one operation byblast welding. The core angle of the female part may be greater thanthat of the male part, so that the wall of the female part deviates fromtheopposed wall of the male part. Likewise, the female part may beformed by longitudinal deformation of the wire followed by the formationof a conical recess in the deformed part.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be furtherdescribed with reference to the accompanying drawings;

FIG. 1 shows two wire ends shaped as a male and a female part;

FIG. 2 the same wire ends brought together for joining and surrounded bya sleeve of explosive;

FIG. 3 a wire end clamped in a tool for axial upsetting of the wire end;

FIG. 4 the same wire end after having been upset under the influence ofan axial force;

FIG. 5 the upset wire end shaped to a female part;

FIGFSa an alternative design of the outermost part of the female part;

FIG. 6 another alternative design for the ends of the wire to be joined.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the drawings, 1a and 1bdesignate the core and 2a and 2b the casing in two wires or rods whichare to be joined. The lefthand wire end is shaped as a male part with aconical point 3 with a cone angle a, the righthand wire end as a femalepart with a double conical recess 4 with a cone angle a in the core anda cone angle [3 in the casing. Since the recess is in the form of adouble cone with the angle a B the area A of the conical surface 5 willbe greater than the area B of the conical surface 6. The casing 2a willtherefore overlap the casing 2b at the joint. The conical recess 4 isexpanded so that a gap 7'is formed when the ends of the wires are fittedtogether, the size of this gap increasing with the distance from thecentre of the wire. A sleeve 8 of explosive is fitted around the jointwith an annular firing mechanism 9 connected to a release means, notshown, by means of a cable 10. It may be advisable to upset the ends ofthe wires axially so that their diameter increases as much as thediameter decreases due to the blast force during the explosion jointing.When the explosive. sleeve is triggered the wire is subjected to apressure wave moving to the left which forces the material lla and 2a inthe female part with considerable force against the material 1b and 2bin the cone 3 in the male part. During the actual joining process theends of the wire are fixed in relation to each other in a fixture, notshown. Any upset which may be formed at the joint by the casing 1aoverlapping the casing 1b should be removed before the wire is drawn tosmaller diameter in the drawing plates. When the recess 4 is expanded sothat the cone angle is greater than the cone angle a of the male part inorder to produce the gap 7 when the wire ends are fitted together, theoutermost bevelled part of the copper casing may crack or be stretcheddifferently at different parts of the circumference. An alternativeprocess which avoids this drawback is shown in FIGS. 3 5. By upsettingthe wire end which is to form the female part in a tool having twoclamps 11 which fix the end of the wire axially, it can be given such ashape that the conical recess 4 can be given the desired cone anglewithout the previously mentioned expansion. The wire end a is insertedin the clamps 11 which provide a substantially conical opening. A tool,not shown, affects the wire end 12 with a force P so that the wire end ais axially upset and thus deformed to the shape determined by the toolclamps 11, as shown in FIG. 4. The outer part 13 which has not beencompletely in contact with the tool clamps 11 must be removed. The wireend is cut along a line 14. The conical recess can be shaped in variousways. The most simple design is shown in FIG. where the recess 4 iscompletely conical. Another design is shown in FIG. 5a where the recess4 has a smaller cone angle in the outer part, the copper casing 2a, thanin the inner part, the aluminium core 1a. This means than the conicalcopper surface 5 in the female part is wider than the conical coppersurface 6 of the male part. The widths are A and B, respectively. Thismeans that the surface 5 will completely cover the surface 6 at thejoint.

In the alternative method according to FIG. 6, the diameter of the wireend b is reduced before it is provided with a conical point. It is thenpossible to eliminate the expansion of the wire end a and in spite ofthis acquire a satisfactory connection between the casings 1b and 2b.Furthermore, it has been found that the explosion gases damage thesurface of the casing 2b at the side of the joint less in thisembodiment than in the other embodiments. The gap 7 has substantiallythe same width along the entire length of the joint. The

male part is provided with a guide point 16 which positions it bothradially and axially in the female part and determines the size of thegap 7.

I claim:

1. Method ofjoining wire of compound material having a core of aluminiumand a casing of copper, which comprises shaping two ends of said wire tobe joined to form male and female parts, inserting the male part so farin the female part that the inner surface of the casing of the femalepart partly covers the unpointed, unshaped part of the casing of themale part, applying a sleeve of explosive around the joint anddetonating it so that the core and casing of one wire end are joined tothe core and casing of the other wire end in one operation by means ofexplosion welding.

2. Method according to claim 1, in which a gap is formed between the twowire ends when they are brought together.

3. Method according to claim 2, in which the shaping comprisesshapingthe male and female parts differently so that the gap formed between thetwo wire ends, which are brought together, increases towards theperiphery of the wire.

4. Method according to claim 1, in which the shaping comprises shapingthe male part with a conical point and the female part with a conicalrecess.

5. Method according to claim 4, in which the shaping comprises expandingthe conical recess of the female part with a cone angle less acute thanthat of the male part.

6. Method according to claim 5, in which the shaping comprises shapingthe female part with a conical recess which at the outer portion definedby the casing has a smallercone angle than the inner portion.

7. Method according to claim 4, in which the shaping comprises upsettingthe wire end which is to form the female part to conical form, andthereafter providing it with a conical recess.

8. Method according to claim 4, in which the shaping comprises machiningthe wire end which is to form the male part to a smaller diameter andproviding it with a conical point.

9. Method according to claim 1, which comprises upsetting the wire endsaxially to greater diameter before shaping them to male and femaleparts.

1. METHOD OF JOINING WIRE OF COMPOUND MATERIAL HAVING A CORE OF ALUMINUMAND A CASING OF COPPER, WHICH COMPRISES SHAPING TWO ENDS OF SAID WIRE TOJOINED TO FORM MALE AND FEMALE PARTS, INSERTING THE MALE PART SO FAR INTHE FEMALE PART THAT THE INNER SURFACE OF THE CASING OF THE FEMALE PARTPARTLY COVERS THE UNPOINTED, UNSHAPED PART OF THE CASING OF THE MALEPART, APPLYING A SLEEVE OF EXPLOSIVE AROUND THE JOINT AND DETONATING ITSO THAT THE CORE AND CASING OF ONE WIRE END ARE JOINED TO THE CORE ANDCASING OF THE OTHER WIRE END IN ONE OPERATION BY MEANS OF EXPLOSIONWELDING.
 2. Method according to claim 1, in which a gap is formedbetween the two wire ends when they are brought together.
 3. Methodaccording to claim 2, in which the shaping comprises shaping the maleand female parts differently so that the gap formed between the two wireends, which are brought together, increases towards the periphery of thewire.
 4. Method according to claim 1, in which the shaping comprisesshaping the male part with a conical point and the female part with aconical recess.
 5. Method according to claim 4, in which the shapingcomprises expanding the conical recess of the female part with a coneangle less acute than that of the male part.
 6. Method according toclaim 5, in which the shaping comprises shaping the female part with aconical recess which at the outer portion defined by the casing has asmaller cone angle than the inner portion.
 7. Method according to claim4, in which the shaping comprises upsetting the wire end which is toform the female part to conical form, and thereafter providing it with aconical recess.
 8. Method according to claim 4, in which the shapingcomprises machining the wire end which is to form the male part to asmaller diameter and providing it with a conical point.
 9. Methodaccording to claim 1, which comprises upsetting the wire ends axially togreater diameter before shaping them to male and female parts.